Residual depressive symptoms (RDS) following remission of major depressive disorder (MDD) are reported by 80-90% of adults receiving first-line antidepressant pharmacotherapy and carry an elevated risk for a chronic course of illness, rapid relapse and functional impairment (Nierenberg et al., 2010). Strategies for managing residual symptoms, however, have met with mixed success (Fava et al., 2007). Mindful Mood Balance (MMB; R34 MH0877223) is an individually tailored, web-based treatment designed to train remitted depressed patients to disengage from dysphoria-activated depressogenic thinking that perpetuates RDS and increases risk for relapse/recurrence. MMB was developed to increase access to Mindfulness-Based Cognitive Therapy (MBCT; R01 MH066992), an empirically supported prophylactic group treatment that can be easily sequenced with acute phase antidepressant pharmacotherapy. Results from our open trial of MMB (N=100) showed an effect size of d=1.09 for pre to post treatment reductions in depression scores among patients with RDS and d=1.54 in a quasi-experimental comparison to patients receiving usual care, with an on average reduction of 1.98 points on the PHQ-9 for MMB patients. We now propose a pragmatic randomized clinical trial of MMB to evaluate its effectiveness in reducing RDS in recurrently depressed patients. Patients will be members of Kaiser-Permanente Colorado (N = 460), aged 18 to 75, who score >5 and <9 on the PHQ-9, in remission from MDD and will be randomized 1:1 to either the usual depression care pathway (DepCare) or Mindful Mood Balance (MMB)+DepCare. We plan to test whether patients receiving MMB+DepCare will show greater reductions in RDS at both 8 week and 12 months follow up, than those receiving DepCare alone. We are also interested in examining whether fewer patients in MMB+DepCare will relapse over the follow up and will have higher end state functioning and quality of life. In order to examine the costs associated with adding this online treatment to the Depression Care Pathways at KPCO, we will calculate the marginal costs per additional number of depression free days (DFDs) for patients. Resolution of RDS can reduce the enormous personal and social costs experienced by Americans with this persistent symptom burden.